FIG. 1A is a cutaway perspective view of an optical module in the prior art, and FIG. 1B is a sectional view of the optical module shown in FIG. 1A.
This optical module includes a housing 4 having an opening 2 extending from the outer side to the inner side of the housing 4, a ring 6 fixed to the housing 4, a ferrule 10 fixed to the ring 6 under the condition where it is inserted in the ring 6, an optical fiber 8 fixed to the ferrule 10 under the condition where it is inserted in a center hole of the ferrule 10, and an optical device 12 such as a light receiving element provided in the housing 4 and adapted to be optically coupled with the optical fiber 8. Further, a manufacturing method for this optical module includes, for example, the first step of inserting into the ring 6 the ferrule 10 under the condition where the optical fiber 8 is inserted and fixed in the center hole of the ferrule 10, bringing an end surface of the ring 6 into close contact with an outer surface of the housing 4, and adjusting a relative positional relationship between the ferrule 10 and the ring 6 and a relative positional relationship between the ring 6 and the housing 4; and the second step of fixing the ferrule 10 to the ring 6 and fixing the ring 6 to the housing 4.
In the prior art mentioned above, the housing 4 can be reduced in height to thereby reduce the size of the optical module. However, when the height of the housing 4 is reduced, the wall thickness of the ring 6 is reduced to cause a reduction in mechanical strength. To prevent such a reduction in mechanical strength, there has been proposed a construction provided with a reinforcement member 14 so as to cover the ring 6 and the ferrule 10 as shown in FIG. 2 (Daniel S. Bargar: "An Automated Fiber Alignment, Fixing, and Hermetic Sealing System", SPIE Vol. 994, Optoelectric Materials, Devices, Packaging, and Interconnects II (1988), P. 11-17). According to this construction, a bending stress generating by application of an external force is absorbed by the reinforcement member 14, and is not directly applied to the ring 6. However, since the wall thickness of the reinforcement member 14 must be increased in order to obtain an effective strength, this structure is not always suitable for the reduction in size of the optical module.
It is an object of the present invention to provide an optical module and a manufacturing method therefor which can improve a mechanical strength and are suitable for a reduction in size.
It is another object of the present invention to provide an optical module which can effect hermetic seal, be suitable for a reduction in size, and be excellent in productivity.